Characterization of and correction for artifacts in linogram MRI

Abstract

Chemical shift differences, field inhomogeneity, and gradient nonlinearity result in artifacts in magnetic resonance imaging. Three artifacts are characterized for linogram imaging and it is shown that, based on computer simulations and theory, linogram MRI behaves similarly to 2DFT. A correction technique similar to a scheme for 2DFT imaging based on the Dixon technique and coordinate transform methods is proposed. The algorithm is applied to correct for field inhomogeneity and gradient nonlinearity-induced artifacts in both simulations and images of a clinical phantom. The results show good correlation with the theory. It is concluded that linogram imaging offers certain attractive features of both 2DFT and PR imaging techniques, and is a potentially viable alternative to PR imaging in the presence of field inhomogeneity.

Effect of slice angle on inhomogeneity artifact and its correction in slice‐selective MR imaging

“…The oblique slice angle effect in both the regular and VAT sequences cannot be applied to the projection reconstruction because the readout direction is rotated by 1808 (3,25,26). The projection reconstruction has been widely used in routine MR imaging because of its intrinsic immunity to the motion and flow artifacts as first reported by Jung and Cho (12,27).…”

A dual approach to linogram imaging for MRI

“…1 in the above equation corresponds to the projection data, gr(u, v), and Eq. [7] represents the one-dimensional Fourier transform of projection data (see Fig. 1) along u.…”

Elimination of nyquist ghosts in MRI by using fast linogram imaging

“…In the discussion below, we assume that 2 N readout points and N total views are acquired for reconstruction on a N X N grid. Note that the additional factor of 2 is due to the different sampling requirements of the linogram geometry in comparison with the two-dimensional I T geometry (9). The number of views ac- ure 4.…”

“…Our earlier work on linogram imaging has shown that this method offers similar motion robustness to projection reconstruction-based imaging (8). Additionally, standard linogram imaging behaves similarly to two-dimensional Fourier transform (FT) techniques in the presence of chemical shift and field inhomogeneity (9). The resulting geometric distortion and amplitude modulation can be corrected for accurately and in a computationally inexpensive manner when compared with projection reconstruction (PR) imaging, in which spatially varying blurring is dimcult to correct for.…”